Biomechatronics mimics how the human body works. For example, four different steps must occur to be able to lift the foot to walk. First, impulses from the motor center of the brain are sent to the foot and leg muscles. Next the nerve cells in the feet send information, providing feedback to the brain, enabling it to adjust the muscle groups or amount of force required to walk across the ground. Different amounts of force are applied depending on the type of surface being walked across. The leg's muscle spindlenerve cells then sense and send the position of the floor back up to the brain. Finally, when the foot is raised to step, signals are sent to muscles in the leg and foot to set it down.

The controller in a biomechatronic device relays the user's intentions to the actuators. It also interprets feedback information to the user that comes from the biosensors and mechanical sensors. The other function of the controller is to control the biomechatronic device's movements.

The actuator is an artificial muscle. Its job is to produce force and movement. Depending on whether the device is orthotic or prosthetic the actuator can be a motor that assists or replaces the user's original muscle.

Interfacing allows biomechatronic devices to connect with the muscle systems and nerves of the user in order send and receive information from the device. This is a technology that is not available in ordinary orthotics and prosthetics devices. Groups at the University of Twente are making drastic steps in this department. Scientists there have developed a device which will help to treat paralysis and stroke victims who are unable to control their foot while walking. The researchers are also nearing a breakthrough which would allow a person with an amputated leg to control their prosthetic leg through their stump muscles.

Hugh Herr is the leading biomechatronic scientist at MIT. Herr and his group of researchers are developing a sieveintegrated circuitelectrode and prosthetic devices that are coming closer to mimicking real human movement. The two prosthetic devices currently in the making will control knee movement and the other will control the stiffness of an ankle joint.

As mentioned before Herr and his colleagues made a robotic fish that was propelled by living muscle tissue taken from frog legs. The robotic fish was a prototype of a biomechatronic device with a living actuator. The following characteristics were given to the fish.[2]

A styrofoam float so the fish can float

Electrical wires for connections

A silicone tail that enables force while swimming

Power provided by lithium batteries

A microcontroller to control movement

An infrared sensor enables the microcontroller to communicate with a handheld device

New media artists at UCSD are using biomechatronics in performance art pieces, such as Technesexual (more information, photos, video), a performance which uses biometric sensors to bridge the performers' real bodies to their Second Life avatars and Slapshock (more information, photos,video), in which medical TENS units are used to explore intersubjective symbiosis in intimate relationships.

The demand for biomechatronic devices are at an all-time high and show no signs of slowing down. With increasing technological advancement in recent years, biomechatronic researchers have been able to construct prosthetic limbs that are capable of replicating the functionality of human appendages. Such devices include the "i-limb", developed by prosthetic company Touch Bionics, the first fully functioning prosthetic hand with articulating joints,[3] as well as Herr's PowerFoot BiOM, the first prosthetic leg capable of simulating muscle and tendon processes within the human body.[4] Biomechatronic research has also helped further research towards understanding human functions. Researchers from Carnegie Mellon and North Carolina State have created an exoskeleton that decreases the metabolic cost of walking by around 7 percent.[5]

Despite the demand, however, biomechatronic technologies struggle within the healthcare market due to high costs and lack of implementation into insurance policies. Herr claims that Medicare and Medicaid specifically are important "market-breakers or market-makers for all these technologies," and that the technologies will not be available to everyone until the technologies get a breakthrough.[6] Biomechatronic devices, although improved, also still face mechanical obstructions, suffering from inadequate battery power, consistent mechanical reliability, and neural connections between prosthetics and the human body.[7]